I've been making videos in Premiere Pro for the past year with no problem, and this is my first attempt in the last month, having just re-formated my machine, installed CC and updated Graphics cards (from 2 x GTX 580s with which I had none of the below problems).

If I create a sequence, create a new 'Black Video' item, drag it to the timeline, then slide the playhead over the video, Premiere Crashes. Tried the same with just an imported JPG, Premiere Crashes.

If I just create a new project in Premiere. Wait for 20 sec, no crash. Import a jpeg to my project (no sequence created, didn't try and preview the jpg or anything), about 2 seconds later, Premiere Crashed. Looks as though by importing a jpeg, Premiere would crash as it tried to display the preview (in the project tab).

Temporary Fix

I went into my project settings (file > project settings > general) and changed the 'Video Rendering and Playback' from 'Mercury Playback Engine GPU Accelleration (OpenCL)' to 'Mercury Playback Engine Software Only'. Videos and Jpegs now playback fine, Premiere does not crash.... it would be nice though to use GPU accelleration of the R9 290s, but as much as I like my games, it's tempting to go back to the GTX 580s as I do a lot with the Adobe suite

Photoshop

I do a lot of professional digital painting, I noticed when using my Wacom Intuos5 (I usew the Cintiq 24HD with GTX580 at work), there was heaps of lag in painting with a standard brush. If I just did a slow stroke, the 'paint' would be lagging behind the brush 5-10mm onscreen.

I tried setting the 'Use Graphics Processor' down to Normal and Basic, and it got worse. I turned 'Use Graphics Processor' off completely which resulted in no real discernible lag, feels very natural as it did with the Nvidia cards. However, because this is turned off, I loose any GPU 'accelerated' advantages like animated zoom, 3D etc.

While I appreciate what you say about Adobe software (having been in the publishing and design industry for 20 years), the CC suite was pretty flawless with the Nvidia cards.... I'm still running my GTX 580 at work and graphics accelleration works fine. I have posted this info on the Adobe forums also.